body
{
    background-color: antiquewhite;
    display: flex;
    justify-content: center;
}
.login-box
{
    position: absolute;
    top: 50%; /*向下定位50% 参照物的50%，此时参照物是body*/
    transform: translateY(-50%);    /*Y轴平移自身的-50%，-上+下*/
    width: 30%;
    background-color: rgba(0,0,0,0.3);
    padding: 50px;
    border-radius: 10px;
    box-shadow: 0px 0px 10px palegreen;
}
.pwd-box
{
    display: flex;
    justify-content: space-between;
    margin:  20px 0px;
}
.pwd-box a
{
    color: white;
    font-size: 15px;
}